Originally Answered: Christians: Dealing with family members?
>> doesn't it say we should confront fellow believers in the Bible?
Not in the way you are doing it. You are basically getting upset and confronting them with your emotions. You are also confronting them with the idea (or the hope) that you can change them or cause them to change. That is not realistic -- and not Biblical. Trying to block someone's progress out of your room is not what Jesus would have done. Laying your hand on your sister to force her to do as you want is also not what Jesus would have done. Turning the other cheek is about getting out of people's way and not trying to force other people to your will.
I can identify with your situation, though, because my wife has a personality much like a combination of both your brother and your sister. Though I do pray for her, mostly I pray for myself that through a Holy Spirit transformation of my character, I will learn to deal with it as Jesus would. I recognize that I cannot change her nor try to make her see how she is and, hopefully, change herself. Instead, I wish to develop the same patient and peaceful demeanor which Christ had when dealing with the Pharisees and the Sadducees. Did He occasionally have critical words for them? Yes. But He was perfect and, therefore, well justified. I am not.
Final advice? All the Bible really has for a formula for dealing with interpersonal troubles is the following:
Mat. 18:15,16 Moreover if thy brother shall trespass against thee, go and tell him his fault between thee and him alone: if he shall hear thee, thou hast gained thy brother. (16) But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established.
In your case, the witnesses should be your parents. If your parents have no control over your brother and sister, then perhaps a knowledgeable and sympathetic friend of theirs outside of the family is your only recourse. Basically, you need a witness which is someone they respect. The rest of the Bible's advice applies to actual, outright, and egregious sin (which troubles getting along inside a family is not in that category).
Mat. 18:17 And if he shall neglect to hear them, tell it unto the church: but if he neglect to hear the church, let him be unto thee as a heathen man and a publican.
So, ignoring someone can be justified. ;-) Just make sure it is done without rudeness and in love.